Qiang Li

Bio: Qiang Li is an academic researcher from Northwestern Polytechnical University. The author has contributed to research in topics: Dielectric & Ceramic. The author has an hindex of 23, co-authored 90 publications receiving 1712 citations. Previous affiliations of Qiang Li include Shenzhen University & Northwestern Polytechnic University.

Giant strain response and structure evolution in (Bi0.5Na0.5)0.945−x(Bi0.2Sr0.7□0.1)xBa0.055TiO3 ceramics

Abstract: The microstructure, electric-field-induced strain, polarization, and dielectric permittivity in (Bi0.5Na0.5)0.945−x(Bi0.2Sr0.70.1)xBa0.055TiO3 (BNBT–xBST) (0 ≤ x ≤ 0.08) electroceramics are investigated. An irreversible transition from rhombohedral and monoclinic coexistence phase to single rhombohedral phase is indicated with the remnant strain Sr = 0.330% at x = 0. As the BST content increases, the ferroelectric order is disrupted resulting in a degradation of the remnant polarization, coercive field, and the ferroelectric-to-relaxor transition temperature (TF–R). The coexistence of ferroelectric relaxor and ferroelectric phase is observed for the optimum composition x = 0.02 at ambient temperature with a large strain of 0.428% at 60 kV/cm (normalized strain Smax/Emax = 713 pm/V). The large strain is contributed by both ferroelectric domain reorientation behavior and the reversible relaxor to ferroelectric phase transition. © 2014 Elsevier Ltd. All rights reserved.

Gas-sensing and electrical properties of perovskite structure p-type barium-substituted bismuth ferrite

Abstract: Pure and Ba-substituted bismuth ferrite (BiFeO3, BFO) powders were successfully synthesized via a sol–gel method. The effects of the Ba-substitution on the morphology, gas-sensing and electrical properties of BFO were studied. The gas-sensing tests show that the sensor based on Bi0.9Ba0.1FeO2.95 (BBFO10) has high sensitivity, quick response, effective selectivity and excellent long-time stability. The conduction mechanism and gas-sensing mechanism of a BBFO10 sample were investigated by the impedance spectroscopy and it was found that the conduction is dominated by p-type hole conduction. The conductivity of the sensor is dependent on the oxygen partial pressures and the type of gas atmosphere. The enhanced gas-sensing performances of the BBFO10 sensor are attributed to the higher oxygen vacancy concentration which was induced by the substitution of Bi3+ ion by an aliovalent Ba2+ ion at the A-site of the perovskite structure.

Solution Combustion Synthesis of Nanoscale Materials

Abstract: Solution combustion is an exciting phenomenon, which involves propagation of self-sustained exothermic reactions along an aqueous or sol–gel media. This process allows for the synthesis of a variety of nanoscale materials, including oxides, metals, alloys, and sulfides. This Review focuses on the analysis of new approaches and results in the field of solution combustion synthesis (SCS) obtained during recent years. Thermodynamics and kinetics of reactive solutions used in different chemical routes are considered, and the role of process parameters is discussed, emphasizing the chemical mechanisms that are responsible for rapid self-sustained combustion reactions. The basic principles for controlling the composition, structure, and nanostructure of SCS products, and routes to regulate the size and morphology of the nanoscale materials are also reviewed. Recently developed systems that lead to the formation of novel materials and unique structures (e.g., thin films and two-dimensional crystals) with unusual...

Magnetically separable nanocomposites based on ZnO and their applications in photocatalytic processes: A review

Abstract: Among the most challenging problems that human beings appear to face are depleting energy sources and increasing environmental pollutions. Heterogeneous photocatalytic processes are the most reward...

Progress in high-strain perovskite piezoelectric ceramics

Abstract: High strain piezoelectric ceramics are the state-of-the-art materials for high precision, positioning devices. A comprehensive review of the latest developments of the various types of perovskite piezoelectric ceramic systems is presented herein, with special attention given to three promising families of lead-free perovskite ferroelectrics: the barium titanate, alkaline niobate and bismuth perovskites. Included in this review are details of phase transition behavior, strain enhancement approaches, material reliabilities as well as the status of some promising applications. This current review describes both compositional and structural engineering approaches that are intended to achieve enhanced strain properties in perovskite piezoelectric ceramics. The factors that affect the strain behavior of high-strain perovskite piezoelectric ceramics are addressed. The reliability characteristics of these high-strain ferroelectrics as well as the recent approaches to the long-term electrical, thermal and time-stability enhancement are summarized. Several promising applications of high-strain perovskite materials are introduced, which take advantages of their characteristics; examples include high-energy storage, pyroelectric and electro-caloric effect and luminescent properties.

Potassium–sodium niobate based lead-free ceramics: novel electrical energy storage materials

Abstract: The development of lead-free bulk ceramics with high recoverable energy density (Wrec) is of decisive importance for meeting the requirements of advanced pulsed power capacitors toward miniaturization and integration. However, the Wrec (<2 J cm−3) of lead-free bulk ceramics has long been limited by their low dielectric breakdown strength (DBS < 200 kV cm−1) and small saturation polarization (Ps). In this work, a strategy (compositions control the grain size of lead-free ceramics to submicron scale to increase the DBS, and the hybridization between the Bi 6p and O 2p orbitals enhances the Ps) was proposed to improve the Wrec of lead-free ceramics. (K0.5Na0.5)NbO3–Bi(Me2/3Nb1/3)O3 solid solutions (where Me2+ = Mg and Zn) were designed for achieving large Ps, and high DBS and Wrec. As an example, (1 − x)(K0.5Na0.5)NbO3–xBi(Mg2/3Nb1/3)O3 (KNN–BMN) ceramics were prepared by using a conventional solid-state reaction process in this study. Large Ps (41 μC cm−2) and high DBS (300 kV cm−1) were obtained for 0.90KNN–0.10BMN ceramics, leading to large Wrec (4.08 J cm−3). The significantly enhanced Wrec is more than 2–3 times larger than that of other lead-free bulk ceramics. The findings in this study not only provide a design methodology for developing lead-free bulk ceramics with large Wrec but also could bring about the development of a series of KNN-based ceramics with significantly enhanced Wrec and DBS in the future. More importantly, this work opens a new research and application field (dielectric energy storage) for (K0.5Na0.5)NbO3-based ceramics.

Hybrid threshold adaptable quantum secret sharing scheme with reverse Huffman-Fibonacci-tree coding

Abstract: With prevalent attacks in communication, sharing a secret between communicating parties is an ongoing challenge. Moreover, it is important to integrate quantum solutions with classical secret sharing schemes with low computational cost for the real world use. This paper proposes a novel hybrid threshold adaptable quantum secret sharing scheme, using an m-bonacci orbital angular momentum (OAM) pump, Lagrange interpolation polynomials, and reverse Huffman-Fibonacci-tree coding. To be exact, we employ entangled states prepared by m -bonacci sequences to detect eavesdropping. Meanwhile, we encode m -bonacci sequences in Lagrange interpolation polynomials to generate the shares of a secret with reverse Huffman-Fibonacci-tree coding. The advantages of the proposed scheme is that it can detect eavesdropping without joint quantum operations, and permits secret sharing for an arbitrary but no less than threshold-value number of classical participants with much lower bandwidth. Also, in comparison with existing quantum secret sharing schemes, it still works when there are dynamic changes, such as the unavailability of some quantum channel, the arrival of new participants and the departure of participants. Finally, we provide security analysis of the new hybrid quantum secret sharing scheme and discuss its useful features for modern applications.